When building with clang, via:
make LLVM=1 -C tools/testing/selftests
Fix this by moving the inline asm to "pure" assembly, in two new files: clang_helpers_32.S, clang_helpers_64.S.
As a bonus, the pure asm avoids the need for ifdefs, and is now very simple and easy on the eyes.
Signed-off-by: John Hubbard jhubbard@nvidia.com --- tools/testing/selftests/x86/Makefile | 2 ++ tools/testing/selftests/x86/clang_helpers_32.S | 11 +++++++++++ tools/testing/selftests/x86/clang_helpers_64.S | 12 ++++++++++++ tools/testing/selftests/x86/fsgsbase_restore.c | 11 +++++------ 4 files changed, 30 insertions(+), 6 deletions(-) create mode 100644 tools/testing/selftests/x86/clang_helpers_32.S create mode 100644 tools/testing/selftests/x86/clang_helpers_64.S
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile index c1269466e0f8..99bc2ef84f5a 100644 --- a/tools/testing/selftests/x86/Makefile +++ b/tools/testing/selftests/x86/Makefile @@ -113,6 +113,8 @@ endef $(eval $(call extra-files,sysret_ss_attrs_64,thunks.S)) $(eval $(call extra-files,ptrace_syscall_32,raw_syscall_helper_32.S)) $(eval $(call extra-files,test_syscall_vdso_32,thunks_32.S)) +$(eval $(call extra-files,fsgsbase_restore_64,clang_helpers_64.S)) +$(eval $(call extra-files,fsgsbase_restore_32,clang_helpers_32.S))
# check_initial_reg_state is special: it needs a custom entry, and it # needs to be static so that its interpreter doesn't destroy its initial diff --git a/tools/testing/selftests/x86/clang_helpers_32.S b/tools/testing/selftests/x86/clang_helpers_32.S new file mode 100644 index 000000000000..dc16271bac70 --- /dev/null +++ b/tools/testing/selftests/x86/clang_helpers_32.S @@ -0,0 +1,11 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * 32-bit assembly helpers for asm operations that lack support in both gcc and + * clang. For example, clang asm does not support segment prefixes. + */ +.global dereference_seg_base +dereference_seg_base: + mov %fs:(0), %eax + ret + +.section .note.GNU-stack,"",%progbits diff --git a/tools/testing/selftests/x86/clang_helpers_64.S b/tools/testing/selftests/x86/clang_helpers_64.S new file mode 100644 index 000000000000..0d81c71cad97 --- /dev/null +++ b/tools/testing/selftests/x86/clang_helpers_64.S @@ -0,0 +1,12 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * 64-bit assembly helpers for asm operations that lack support in both gcc and + * clang. For example, clang asm does not support segment prefixes. + */ +.global dereference_seg_base + +dereference_seg_base: + mov %gs:(0), %rax + ret + +.section .note.GNU-stack,"",%progbits diff --git a/tools/testing/selftests/x86/fsgsbase_restore.c b/tools/testing/selftests/x86/fsgsbase_restore.c index 6fffadc51579..224058c1e4b2 100644 --- a/tools/testing/selftests/x86/fsgsbase_restore.c +++ b/tools/testing/selftests/x86/fsgsbase_restore.c @@ -39,12 +39,11 @@ # define SEG "%fs" #endif
-static unsigned int dereference_seg_base(void) -{ - int ret; - asm volatile ("mov %" SEG ":(0), %0" : "=rm" (ret)); - return ret; -} +/* + * Defined in clang_helpers_[32|64].S, because unlike gcc, clang inline asm does + * not support segmentation prefixes. + */ +unsigned int dereference_seg_base(void);
static void init_seg(void) {